1. Field of the Invention
The present invention relates to a printer for printing a predetermined image on a sheet of a developing paper by exposing a sensitive surface comprised of photosensitive microcapsules on a long photosensitive film to a light image according to a predetermined picture signal to form a photographed film frame, and overlapping and pressing together the exposed surface of the photosensitive film with the developing paper sheet while being moved together
2. Description of the Prior Art
Various types of printing systems are known, such as thermal type, pen type, dot type and ink-jet type, for forming on a piece of printing paper a predetermined image, for example, a television image received by a television receiver or a recorded image recorded on a recording medium, such as, a magnetic tape, optical disc or the like. There is a further printing system in which a surface of a photosensitive film provided with photosensitive microcapsules is exposed to the light corresponding to a predetermined image signal to form a photographed film and the exposed film is overlapped with, and pressed against, a sheet of developing paper for printing a corresponding picture on the developing paper.
For example, in the Japanese Patent Laid-open Gazette No. 59-30537, there is disclosed a printing system using a photosensitive film which has provided thereon very small photosensitive microcapsules which are hardened to be non-destructive or uncrushable by pressure when exposed to predetermined wavelength of light and which contain a coloring precursor substance which, when released by crushing of the respective microcapsules, reacts with a developing material provided on a sheet of developing paper to provide a respective color on the latter. The sensitive surface of the photosensitive film is exposed to, for example, ultraviolet light changing in accordance with the decomposed picture elements of a predetermined picture so that a positive photographed film can be produced. The exposed side of the photosensitive film is overlapped with a sheet of developing paper and pressed thereagainst so that the photosensitive microcapsules not exposed to such light are destroyed or crushed to release the coloring precursor substance enclosed therein, which is transferred to the developing paper. Thus, the predetermined picture is printed on the developing paper.
When carrying out the printing of a picture by the system described above, in order to perform the printing operation with high efficiency or to simplify the necessary mechanism as much as possible, it may be considered to use a so-called continuous type photosensitive film, or a roll of photosensitive film wound on a spool and being long enough to form a great number of frames of photographed film.
Moreover, the printer using this long photosensitive film is generally constructed to provide a constant travel path for the photosensitive film, with exposing means being disposed at a location along such travel path, a roller member disposed after the exposing means to pinch and feed the photosensitive film, so that the photosensitive film is made to travel past and be exposed by the exposing means, and developing paper supplying means which supplies a sheet of developing paper into overlapping relation with the exposed portion of the photosensitive film, whereupon the overlapped sheet of developing paper and the exposed film travel in unison while being pressed together by the roller member so as to achieve the desired printing.
In the above printer, however, when the printing of a picture on the developing paper is completed, the trailing end of the photographed film frame of the photosensitive film, or of the exposed portion thereof, will always be substantially spaced from the exposing means. Thus, when the next-picture or photographed film frame is started exposed, there is a waste of a substantial part of the photosensitive film between the trailing end of the last exposed film frame and the position opposing the exposing means.
This waste of part of the photosensitive film aggregates approximately half the whole length of the related photosensitive film, which is very uneconomical.